1. Field of the Invention
This invention relates generally to devices for removing contaminants from liquids, and more particularly, to a personal portable filter device for attachment to a drinking straw to remove contaminants from liquid, e.g. water, drawn through the straw.
2. Description of the Prior Art
Supplies of potable water are generally treated to remove impurities, including the removal of particulate matter, undesirable odors and tastes, and harmful microorganisms. This treatment is ordinarily accomplished at large community or municipal treatment facilities prior to distribution of the water to its point or points of use. Some users are not on municipal water supply systems, but receive their water from wells or other sources. These users must provide their own water treatment, if any is used, in order to remove contaminants from the water. This is generally accomplished by a fixed water filtration and purification system installed between the source of the water and distribution of the treated water to the point of use.
Although municipal and personal water treatment systems render the water safe for use, some undesirable impurities, such as odor and taste, can still remain. Moreover, municipal and personal water treatment systems can sometimes completely or partially fail, resulting in undesirable impurities remaining in the water supplied to the user.
Additionally, water supplies in some parts of the world are untreated or inadequately treated, with the result that persons using the water may become ill. Even if the potable water supply in some locales is safe to use, and does not produce any adverse affects in the local population, persons travelling to that locale from other areas may become ill after drinking the water due to the presence in the water of microorganisms and intestinal parasites.
Still further, persons hiking or camping in remote areas, or military personnel, may not have ready access to treated water supplies. These persons run the risk of becoming seriously ill if they use untreated water, and since no one can survive for very long without water, they must either carry with them a potable water supply, or treat the water locally obtained. In the past, various chemicals, such as iodine, and/or filtration systems, have been carried by military personnel, hikers, and campers, for example, to treat locally obtained water. While these methods can prevent illness that would otherwise be caused by use of contaminated water, they are inconvenient to use and/or may leave undesirable tastes and odors in the water.
A variety of portable water purification devices for personal use have been developed in the prior art. These are exemplified by U.S. Pat. Nos. 4,995,976, 5,509,605, and 5,688,588. The water purification devices described in these patents comprise a filter device in association with a drinking straw whose proximal end is placed in the mouth of the user, and the distal end is placed in a source or supply of water. The water is drawn by the user through the straw and filter device, which removes contaminants from the water. While these devices function adequately for their intended purpose, they require specially constructed tubular members, and/or are relatively complex and expensive in construction. Further, these devices incorporate multiple purification devices arranged in series, thereby providing resistance to flow of water and may require substantial effort to draw the water through the straw.
Accordingly, there exists a need for a personal portable liquid filter or purification device that is simple and inexpensive in construction, and which does not require an inordinate amount of effort to draw liquid through the device. Moreover, since a specially constructed tubular member for holding the liquid purification device may become damaged or broken during handling and use, or may not be readily available, there is need for a personal portable liquid purification and filtration device which may be attached to a conventional drinking straw or to any other suitable tube, whereby it is necessary only to carry one or more of the purification devices for attachment to a conventional straw or other tube.